One of the great challenges of modern biology is an explanation of aging at the organismal level. The fundamental property of aging is manifest in organisms as complex as humans and as simple as the single-celled yeast, Saccharomyces cerevisiae. The ability to extend life span and forestall senescence has long been the subject of debate and exploration.
Recent studies of the premature aging disease, Werner's syndrome, provide possible clues about the aging process. Beginning soon after puberty, Werner's syndrome patients display many symptoms of old age, including graying and loss of hair, osteoporosis, cataracts, atherosclerosis, loss of skin elasticity and a propensity for certain cancers. Because cells isolated from Werner's patients divide approximately half as many times in culture as those from normal individuals (Salk et al., Cytogenet. Cell. Genet. 30:108 (1981); G. M. Martin, Adv. Exp. Med. Biol. 190:161 (1985)), it is possible that both organismal aging and cellular aging are manifestations of the same process (Lombard and Guarente, Trends Genet. 12:283 (1996)).